A rising incidence of life-threatening systemic fungal diseases, e.g. invasive candidiasis (1C), chiefly among immunocompromised patients, a high attributable mortality (ca. 38% to 49%), and a high rate of therapeutic failure (ca. 20% to 50%) highlight the unmet need for progress in antifungal therapy. Amphotericin B (AmB), a unique broad spectrum antibiotic, remains the drug of choice despite its poor water solubility, challenges in formulation and administration, particularly in its standard formulation, Fungizone(r), and untoward toxicity (dose-limiting nephrotoxicity). Our efforts have demonstrated that DSPE-PEG micelles easily solubilize AmB and deaggregate this membrane-acting drug, resulting in a major reduction of toxicity in vitro and a minor reduction of toxicity in vivo. Significantly, it has been demonstrated that AmB/DSPE-PEG is soluble in water in the presence of NaCI, in contrast to Fungizone(r), and is compatible with 5-FC, a water-soluble antifungal drug, and rapamycin, a poorly water-soluble antifungal drug, which has also been solubilized by DSPE-PEG micelles. Thus, the objective of the proposed research is to explore the potential of this novel form of AmB, utilizing its unique physical stability for combined drug therapy through a single IV access line for the first time, increasing safety, lowering cost, and increasing therapeutic efficacy. It is hypothesized that AmB/DSPE -PEG will be less toxic than Fungizone(r), owing to deaggregation of drug, continuous infusion, and sodium supplementation (0.9% NaCI), infused together in the same aqueous vehicle. It is also hypothesized that AmB/DSPE-PEG can be administered safely with 5-FC or rapamycin/DSPE-PEG in 0.9% NaCI via the same IV access line, increasing antifungal efficacy (additive or synergistic effects). The Specific Aims are to estimate in vitro efficacy of AmB/DSPE-PEG, 5-FC, rapamycin/DSPE-PEG combinations against Candida albicans isolates using the broth microdilution checkerboard method; define the in vivo toxicity of AmB/DSPE -PEG, administered in a sterile NaCI vehicle with and without 5-FC or rapamycin/DSPE-PEG, using Fungizone(r), as a control; define the pharmacokinetics of AmB/DSPE-PEG, AmB/DSPE-PEG + 5-FC, and AmB/ DSPE-PEG + rapamycin/DSPE-PEG in rodents; establish antifungal activity of AmB/DSPE-PEG, 5-FC, or rapamycin/DSPE-PEG in a validated murine model of 1C; and establish antifungal activity of combinations of antifungal agents: AmB/DSPE-PEG + 5-FC or rapamycin/DSPE-PEG in a validated murine model of 1C. [unreadable] [unreadable] [unreadable]